What is the difference between UIView objects and CALayer in iOS development?

UIView is a high-level object that represents a visual element of the user interface in iOS. It is responsible for handling user events, managing the view hierarchy, and rendering content through its associated CALayer.

CALayer is a lower-level object that directly handles graphics rendering and animations. Each UIView contains one CALayer, which manages visual content, shadows, borders, transformations, and animations.

Main differences:

• UIView is a UI object that handles user interaction and events.
• CALayer is responsible for rendering and animation, and does not handle events.
• UIView uses CALayer to display content.

Example:

let view = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
view.backgroundColor = .red

// Working directly with CALayer
view.layer.cornerRadius = 10
view.layer.shadowOpacity = 0.5

Here, UIView manages position and interaction, while CALayer handles visual effects.